The present invention relates to a foldable elongated agricultural sprayer boom for field spraying applications, which provides reliable breakaway structure for permitting an outer section of the boom to pivot relative to an inner section to clear obstructions. The outer section also can be folded back alongside of the inner section. The entire boom will fold forwardly for transport. The inner section of the boom is a composite structure that is lightweight, torsion resistant, and high strength.
Foldable field sprayer boom assemblies used for spraying fields have been used for many years. With larger and larger fields, it is desirable to have the booms as long as possible. Problems are inherent in using such booms since there are obstructions that the outer sections of the boom might strike, so the booms generally are made in more than one section with outer sections being capable of pivoting out of the way of obstructions. Also, the outer sections fold back along the inner sections and the entire boom then folds for transport.
Also, when long booms are used, torsional rigidity is from shock loads caused by uneven ground and the like.
Many agricultural sprayers use breakaway sections for hinging the outer boom section to the inner boom section, for example, U.S. Pat. No. 5,428,091 illustrates such a breakaway boom.
The present invention relates to an agricultural sprayer boom made in at least two separate boom sections, which are hinged together at a desired location. The hinge between the inner section of the boom and the outer boom section is provided with a hydraulic cylinder control that is mounted to a floating or knee action linkage that permits the outer section boom to be raised and lowered at the mid point of the boom, and which will dampen the shock loads from the vehicle traversing rough or uneven ground. The hinge used for coupling the boom sections and mounting the hydraulic cylinder that controls the pivoting of the hinge permits folding of the outer boom section. The outer boom section folds back along side the inner boom section.
The outer end of the outer boom section is also supported on the inner boom section in a manner which permits the outer boom section to pivot to clear obstructions that it may strike, by utilizing a pair of suspension cables extending from a T-shaped upright bracket at the hinge at the inner end of the outer boom section. The cables carry tension load, and prevent the outer boom section from sagging when in use, and will maintain the outer boom section in a horizontal position. When the outer boom section engages an object during travel, the outer boom section will pivot about an upright axis, and as it pivots, one of the cables will be placed under greater tension, and the other cable will become slack, automatically. As the outer boom section pivots about the upright axis, the geometry is such that the outer end of the outer boom section will be caused to rise by the cable as the outer end moves through an arc about the upright pivot axis at its inner end. In this manner, the outer boom section will slide around and tend to rise over obstructions at the same time. The outer boom section will pivot to clear an obstruction a full 90xc2x0 while supported by one or the other of the cables.
The spray boom is mounted onto a frame on a movable support, which can be a self-propelled vehicle or a towed trailer. The frame that mounts the boom can be raised and lowered so that the inner boom section will be raised. When the boom sections are to be folded for transport, the outer boom section is folded back alongside the inner boom section, using the hydraulic cylinder that controls the hinge that permits such pivoting. Also a second hydraulic cylinder is used for moving the inner boom section about an upright pivot to a folded position. The inner boom section also has a tension cable support connected from the frame to the T-bracket at the outer end. The cable is mounted so it causes the outer end of the inner boom section to tilt upwardly so that it nests close to the side of the supporting frame and vehicle.
It is also to be understood that there are folding boom sections extending from opposite sides of the supporting frame or vehicle, and each one is a mirror image of the other. Stated another way, there are two of the inner boom sections and mounted to the opposite sides of the support frame, and each of the inner boom sections will support an outer boom section as described.